1) Artificer 2) David bushnell 3) Discoverer 4) Father of the submarine 5) Inventor 6) Submarine inventor David 
David Bushnell noun American inventor who in 1775 designed a man-propelled submarine that was ineffectual but subsequently earned him recognition as a submarine pioneer (1742-1824)
1742?–1824, U.S. inventor: pioneered in submarine construction.